Patent Application
20100092831
This patent application claims the benefit of co-pending German Patent Application No. DE 102008051742.9, filed Oct. 15, 2008, the entire teachings and disclosure of which are incorporated herein by reference thereto.
The present invention relates to a fuel cell for a fuel cell system, in particular in a motor vehicle. The invention furthermore relates to a fuel cell system equipped with such a fuel cell.
Fuel cells or fuel cell systems can be used on motor vehicles as an additional or sole electrical power supply. They are independent of the internal combustion engine of the respective vehicle and can thereby contribute to a savings in fuel.
Conventionally, a fuel cell comprises a plurality of disc-shaped fuel cell elements in which an electrolyte separates an anode chamber from a cathode chamber. The fuel cell elements are constructed one atop the other perpendicular to their disc plane and thereby form a fuel cell stack.
In order to achieve the most effective possible conversion of the hydrogen contained in the anode gas with the oxygen contained in the cathode gas, each fuel cell element can have a plurality of through openings that form a plurality of anode gas inlets communicating with the anode chamber, a plurality of anode gas outlets communicating with the anode chamber, a plurality of cathode gas inlets communicating with the cathode chamber, and a plurality of cathode gas outlets communicating with the cathode chamber. In the assembled fuel cell stack, the through openings of the individual fuel cell elements align and thereby form a plurality of anode gas inlet canals, a plurality of anode gas outlet canals, a plurality of cathode gas inlet canals, and a plurality of cathode gas outlet canals. Advantageously, all inlet canals are connected on a first front face of the fuel cell stack with corresponding supply lines for anode gas and cathode gas, while all outlet canals are connected on the other front face of the fuel cell stack with corresponding removal tubes or lines. In order to now be able to integrate in proper form such a fuel cell in a fuel cell system, a relatively high number of connections must accordingly be realised. Furthermore, a comparably large amount of available space is required in order to be able to lay the many connection lines.
The present invention addresses the problem of providing an improved embodiment for a fuel cell or for a fuel cell system that is characterised in particular in that it makes possible a particularly compact arrangement of the fuel cells within the fuel cell system.
According to the invention, this problem is solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.
The invention is based on the general concept of impinging the fuel cells with the anode gas and the cathode gas in the counter current. A higher conversion rate altogether is achieved in this manner. This increased conversion rate furthermore makes it possible within the respective fuel cell elements to drastically reduce the number of required through openings. Accordingly, it is suggested to equip each fuel cell element with only precisely four through openings, namely with an anode gas inlet, an anode gas outlet, a cathode gas inlet, and a cathode gas outlet. Accordingly, the entire fuel cell stack has in the assembled state only four canals, namely an anode gas inlet canal, an anode gas outlet canal, a cathode gas inlet canal, and a cathode gas outlet canal. It is obvious that this reduced number of canals is tremendously easier to connect to corresponding lines for supplying and removing anode gas or cathode gas. At the same time, the reduced assembly difficulty is accompanied by a considerably reduced space requirement, which space can be used differently. For the counter current impingement of the fuel cells suggested here, it has been proven particularly advantageous in conjunction with the precisely four through openings per fuel cell element to arrange within each fuel cell element the anode gas inlet and the anode gas outlet in diametrically opposite corner regions of the respective fuel cell element. Accordingly, the anode gas flows through the anode chamber of the respective fuel cell element diagonally. In this manner, an increased exposure time results for the anode gas within the anode chamber, which makes an improved conversion possible.
Preferably, the fuel cell stack is provided with end plates on the front face side, which end plates make possible the different connections for connecting the four canals to corresponding tubes and lines. Corresponding to the counter current impingement, an anode gas inlet connection is formed on the one end plate, while a cathode gas inlet connection is formed on the other end plate. In order to simplify the circuitry and thus the integration of the fuel cell into the fuel cell system, it can be provided according to an advantageous embodiment to configure the cathode gas inlet connection and a cathode gas outlet connection on the same end plate. Additionally or alternatively, it can be provided to configure the cathode gas inlet connection and the anode gas outlet connection on the same end plate. Furthermore, one of the end plates can be equipped with a recirculation connection that communicates with the anode gas outlet canal. This recirculation connection can, in particular, be configured on the end plate opposite the anode gas outlet connection. The suggested arrangements for the different connections make possible a particularly compact design of the fuel cell system.
Additional important features and advantages of the invention can be found in the dependent claims, in the drawings, and in the pertinent description of the figures with reference to the drawings.
It is understood that the features described above and those to be described in what follows can be used not only in the particular cited combination, but also in other combinations or independently without departing from the scope of the present invention.
Preferred embodiments of the invention are shown in the drawings and are described in more detail in the following description, the same reference numerals referring to components which are the same or functionally the same or similar.
It is schematically shown in
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternating, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
Corresponding to
Corresponding to
The fuel cell stack 3 moreover comprises two end plates, namely one first or lower end plate 18 and one second or upper end plate 19. In
In the example, the cathode gas outlet connection 24 and a cathode gas inlet connection 23 are configured on the same end plate 19, while the anode gas inlet connection 21 and the anode gas outlet connection 22 are configured on different end plates 18, 19. In the examples shown in
Corresponding to
In the example, a reformer 37 is furthermore provided by means of which the anode gas can be produced. The reformer 37 has a combustion gas outlet 38 that is communicatingly connected to the anode gas inlet connection 21 of the fuel cell stack 3. The reformer 37 generates a synthetic combustion gas, or syngas, that can be used as anode gas. It contains hydrogen gas. Advantageously, the reformer 37 can catalytically reform. In principle, a steam reformation is also conceivable.
In the examples shown, a heat exchanger 39 is moreover provided that connects the burner exhaust gas coming from the residual gas burner 33 with cathode gas in a heat-transferring manner, said mixture being intended to be supplied to the fuel cell 1. In the advantageous embodiment shown here, the heat exchanger 39 and the residual gas burner 33 are arranged on the same end plate, that is to say on the upper end plate 19 here. A cathode gas outlet 40 of the heat exchanger 39 is communicatingly connected to the cathode gas inlet connection 23 of the fuel cell stack 3.
The cathode gas is preferably air. The supply of air to the heat exchanger 39 is realised by means of a conveyor device 41, for example a blower that at the same time also supplies the residual gas burner 33 with air. This air supply of the residual gas burner 33 can be used for cooling. Accordingly, an outlet side 42 of the conveyor device 41 is, on the one hand, connected to a cathode gas inlet 43 of the heat exchanger 39 and, on the other hand, is connected to a cooling gas inlet 44 of the residual gas burner 33.
Moreover, the fuel cell systems 2 shown here are respectively equipped with an additional conveyor device 45 that can likewise be a blower or a compressor or a pump. By means of this conveyor device 45, recirculated anode gas or recirculated anode off-gas is supplied to the reformer 37. Depending on the resistance to heat of the conveyor device 45, a recirculation heat exchanger 46 can additionally be provided, corresponding to
The fuel cell systems 2 shown here, which are configured particularly compactly, characterise themselves in particular by the fact that the residual gas burner 33 and the heat exchanger 39 are positioned within the fuel cell 1 with regard to a projection that is oriented perpendicularly to the stack direction of the fuel cell elements 4. In the same direction of projection, the reformer 37 is also housed within the fuel cell 1; however, on a side facing away from the residual gas burner 33. In this manner, a particularly compact outline for the fuel cell system 2 results. In the embodiment shown in
All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102008051742.9 | Oct 2008 | DE | national |
